Vacuum extraction apparatus for treating moving, liquid-impregnated permeable webs of material, such as fabrics, to remove liquid and chemicals contained therein are well known in the prior art. Certain of such apparatus and equipment are described in the following U.S. patents:
______________________________________ U.S. Pat. No. Smith U.S. Pat. No. Cecere 1,576,679 3,735,444 U.S. Pat. No. Pieron U.S. Pat. No. Araoka 1,759,804 4,191,612 U.S. Pat. No. Gerard, U.S. Pat. No. Grondin, 2,164,174 et al. 4,301,602 et al. U.S. Pat. No. Rose, 2,792,587 et al. ______________________________________
In use of vacuum extraction equipment for treatment of textile fabrics, it is a practice to pass a continuous length of fabric impregnated with a liquid, such as water or a liquid composition containing a chemical finish or dyestuff, across an upwardly disposed longitudinal slot of a vacuum pipe extending across the path of movement of the fabric. The interior of the pipe is connected to a source of vacuum which is manually or automatically regulated at a desired reduced pressure to suck liquid and chemicals from the fabric through the slot and into the pipe and thus control the amount of liquid and chemical remaining on the fabric. Because fabrics treated on such vacuum extraction apparatus vary in width, and also can shift slightly from side to side during their guidance over the vacuum slot, it is necessary that the transverse length of the vacuum slot be sufficient to ensure that suction is applied across the full width of the fabric during treatment.
It is a practice to provide means for sealing the ends of the pipe vacuum slot outside the side edges of a moving fabric to maintain a desired vacuum and suction through the fabric during extraction. Certain vacuum slot sealing devices are disclosed in the following U.S. patents:
______________________________________ U.S. Pat. No. Smith U.S. Pat. No. Rose, et al. 1,576,679 2,792,587 U.S. Pat. No. Gerard, et al. U.S. Pat. No. Cecere 2,164,174 3,735,444 U.S. Pat. No. Grondin, et al. 4,301,602 ______________________________________
It is also known to employ a vacuum slot sealer for such vacuum extraction equipment which comprises an elongate plastic tube suspended by springs along the vacuum slot of the vacuum pipe so that the ends of the tube outside the fabric side edges reside in and seal the outer exposed end portions of the slot during fabric movement thereacross. It is further known to provide an automatically adjustable vacuum slot sealing device having a flexible sealing strip attached at one end to the end of the vacuum pipe and carried in roller form on a carrier which moves along the vacuum slot in response to fabric edge-sensing means to adjustably close the ends of the vacuum slot up to the side edges of the moving fabric.
U.S. Pat. No. 2,792,587 discloses a vacuum slot sealer for each end portion of a longitudinally slotted vacuum pipe of a cloth-treating machine which comprises a flexible sealing strip anchored at one end to a vertical support on the end of the pipe. A pivotable lever mounted intermediate its ends upon the upper end of the vertical support is connected to the unsecured end of the flexible sealing strip, and a counterweight connected to the other end of the lever counterbalances the sealing strip as it raises and lowers out of and into engagement with the vacuum slot to seal the pipe slot outside the side edges of cloth passing thereover. The counterweight is manually adjusted to change the counterforce applied for the particular cloth width being processed and for the particular level of vacuum being employed in the vacuum pipe.